Steering wheel

ABSTRACT

A steering wheel made according to the present disclosure has a composite rim core construction that is secured to a pair of radially extending steering wheel spokes. The lower half of the steering wheel rim is relatively rigid and the upper half of the steering wheel rim has a leaf spring core which bends upon impact whereby a portion of the load of the impact is absorbed.

BACKGROUND OF THE DISCLOSURE

The present disclosure relates to steering wheels for a motor vehicle,and more particularly to steering wheels which have a rim thatresiliently deflects under an impact load so as to absorb a portion ofthe load. The invention of this patent is an improvement upon prior artsteering wheels such as shown in U.S. Pat. Nos. 3,321,996 and 3,456,526.

BRIEF SUMMARY OF THE DISCLOSURE

In the preferred embodiment of the present invention, a steering wheelhas a hub from which a pair of spokes radiate. A rim core assembly ofcomposite construction is secured to the spokes. The ends of the spokesare welded to an arcuate lower rim core portion of relatively rigidconstruction. An upper arcuate rim core portion is formed of flat leafspring steel and is riveted to the ends of the lower rim core. Thesteering wheel spokes and the upper and lower rim core portions areencased in a plastic material.

The steering wheel is intended for use in a motor vehicle. In the eventan impact load parallel to the axis of the steering wheel is imposedupon the upper portion of the steering wheel rim, the rim will deflectdue to the resiliency of the leaf spring core whereby a portion of theenergy of the impact load will be absorbed.

BRIEF DESCRIPTION OF THE DRAWINGS

The many objects and advantages of a steering wheel constructed inaccordance with this invention will become apparent upon considerationof the following detailed discussion and the accompanying drawings, inwhich:

FIG. 1 is a plan view of a steering wheel constructed in accordance witha preferred embodiment of the invention;

FIG. 2 is a side elevational view of a portion of the rim structure ofthe steering wheel of FIG. 1;

FIG. 3 is a sectional view taken along section line 3--3 of FIG. 1showing the connection between the end of one of the spokes and the rimcore;

FIG. 4 is a sectional view taken along section line 4--4 of FIG. 1;

FIG. 5 is an elevational view of a portion of the rim core constructiontaken in the direction of arrow 5 of FIG. 1; and

FIG. 6 is a side elevational view of a portion of a rim core accordingto an alternate embodiment of the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now to the drawings wherein the presently preferredembodiments of this invention are illustrated, FIG. 1 discloses asteering wheel 10 having a unique composite rim construction. Thesteering wheel 10 has a hub 12 for attachment to a steering shaft. Leftand right spokes 14 and 16 extend upwardly from the hub 12. It will beseen in FIG. 1 the spokes 14 and 16 are of dogleg construction havingdownwardly turned ends.

The rim for the steering wheel 10 includes a lower rim core portion 18formed from a rigid round bar. As seen in FIG. 1, the lower rim core 18has a semi-circular shape in the plan view. The outer ends of the spokes14 and 16 are welded to the core 18 near its ends as seen in FIG. 3. Theleft and right ends 20 and 22 of the core 18 extend beyond the pointwhere the left and right spokes 14 and 16 are connected to it. The coreends 20 and 22 have a semi-circular cross section with a flat uppersurface as seen in FIGS. 2 and 4.

The core 24 for the upper half of the rim of the steering wheel 10comprises a flat leaf spring 24 that is formed into approximately onehalf of a circle. The ends of the semi-circular leaf spring 24 arepositioned on the flat surfaces of the ends 20 and 22 of the lower rimcore 18. A right, relatively short, arcuate leaf spring member 26 ispositioned on top of the right end of the leaf spring 24 and a pair ofrivets 28 extend through the arcuate spring 26, the leaf spring 24 andthe end 22 of the rim core 18 whereby these members are rigidly securedtogether.

Similarly, a short arcuate leaf spring 30 overlays the left end of theleaf spring 22. A pair of rivets 32 secure the left end of thesemi-circular spring 24 and the arcuate spring 30 to the flat surface ofthe left end 20 of the rim core 18.

A metal band 34 encircles the arcuate leaf spring 26 and thesemi-circular leaf spring 24 adjacent the end of the spring 26.Similarly, a band 36 secures the upper end of the arcuate spring piece30 to the semi-circular spring 24.

In one embodiment of the invention the main arcuate leaf spring 24 hadan arcuate length equal to 203° and the rod 18 had an arcuate extentequal to 190°. This arrangement provides a 161/2 ° overlap at the leftand right junctures of the spring 24 and the rod 18.

The core of the rim which comprises the lower core member 18 and theleaf springs 24, 26 and 30 is encased in a plastic covering 38 whichgives a decorative appearance to the steering wheel 10 and provides acomfortable surface to be gripped by a vehicle operator. In addition, adecorative covering (not shown) may be provided for the spokes 14 and16.

It will be noted from FIG. 4 that the semi-circular leaf spring member24 has a rectangular shape in cross section as does the short arcuatespring members 26 and 30. These members have flat upper surfaces thatare parallel to a plane perpendicular to the axis of rotation of thesteering wheel. In the event an impact load is imposed upon the upperhalf of the steering wheel in a direction parallel to the axis ofrotation of the wheel, the leaf spring core for the wheel rim willpermit the rim to deflect and to absorb a portion of the impact load. Asimilar load upon the lower rim core 18 will not produce such adeflection.

The arcuate leaf spring members 26 and 28 serve to resist localizedstressing of the semi-circular spring member 24 when it is subjected toan impact load. The arcuate spring members 26 and 30 also facilitate theattachment of the main energy absorbing spring 24 to the rigid core 18for the lower half of the wheel 10.

During the normal operation of the steering wheel 10, the orientation ofthe springs 24, 26 and 30 will provide a construction that will resistdeflection of the upper portion of the rim with respect to a generallytangential force such as exerted by a vehicle operator when turning thewheel 10.

ALTERNATE EMBODIMENT

FIG. 6 discloses an alternate construction of the steering wheel rimcore. In this embodiment, rod stock is bent into a semi-circular shapeto form a rim core member 50 similar to the member 18 of FIG. 1. It iswelded to the ends of the spokes 14 and 16 the same as member 18.

The rim core member 50 differs from member 18 in the configuration ofits end portions that extend beyond the spokes 14 and 16. In FIG. 6, theleft end portion of member 50 has a progressively smaller crosssectional area. It comprises a bent portion 52, an adjacent portion 54,an intermediate portion 56 and an end 58. Portion 54 is bigger inthickness and cross sectional area than portion 56 and portion 56, inturn, is bigger in thickness and cross sectional area than the end 58.

Portions 54 and 56 are provided with a flat mounting surface 60 thatconnects with a curved surface 62. The flat surface 60 is depressed outof the plane containing the upper surface of the body portion of themember 50, that is, the portion of member 50 between its attachment tothe spokes 14 and 16. Drilled holes extend through the portions 54 and56 for the purpose of accommodating rivets.

A pair of leaf spring members 64 and 66 have a generally semi-circularconfiguration in the plan view. Each of these springs is identical tospring 24. Spring 64 is supported on the surface 60. In one embodimentthe springs 64 and 66 were constructed with an arcuate extent of 203°.

Each of the leaf springs 64 and 66 is provided with a pair of holes thatare in alignment with the drilled holes in the member portions 54 and56. Rivets 68 and 70 extend through these holes and secure the springs64 and 66 to the end portion of the rigid rim core member 50. A metalband 72, similar to the band 34 of FIG. 1, encircles the end 58 of themember 50 and the two leaf springs 64 and 66.

FIG. 6 shows the construction at the right side of the rim core. Theconstruction of the juncture between the left ends of the springs 64 and66 and the left end of the member 50 is similar.

The embodiment of FIG. 6 provides a construction for the end portions ofthe rigid core member 50 that is slightly resilient so as to reducestress concentrations when the leaf spring members 64 and 66 aredeflected under an impact load. In this embodiment two fullsemi-circular leaf spring members 64 and 66 extend from one end to theother end of the rigid core member 50. This arrangement permits aconstruction having a desired degree of resiliency with respect to animpact load upon the upper portion of the rim that is parallel to theaxis of rotation of the steering wheel. No partial or short leaf springsare used in this embodiment.

The curve surface 62 reduces stress concentrations in the leaf springs64 and 66 when they are flexed under an impact load. The band 72 servesto reinforce the leaf spring members 64 and 66 when they are flexedrearwardly such as when a motor vehicle operator grasps the upperportion of the steering wheel and exerts a rearward load upon it. Thismay occur when the operator is first seating himself behind the steeringwheel.

METHOD OF MANUFACTURE

The steering wheel of FIG. 6 is manufactured by machining the hub 12 andattaching the inner ends of the spokes 14 and 16 to it by means such aswelding. The rim core member 50 is formed from bar stock having acircular configuration in cross section. The stock is bent into asemi-circular shape in plan view to the configuration of FIG. 6 afterthe ends are formed by cold heading.

The leaf spring members 64 and 66 are identical to each other inconstruction and configuration. These members are formed by continuousedge rolling flat spring wire stock so as to produce a helix having alarge number of turns. The number of turns is selected on the basis ofconvenience in handling during the manufacturing operation. Two hundredturns may be an appropriate number. During the winding of the helix, theflat wire stock is notched at 203° intervals (or at such other intervalsas corresponds to the length of the arc of the springs 64 and 66). Apair of holes are drilled through the helical band on either side ofeach notch. These holes will subsequently accommodate the rivets 68 and70.

When the helix is wound to a convenient length, it is cut and thenplaced in a supporting fixture to maintain each turn of the helix inflush engagement with its adjacent turn. The helix is then heat treatedin an oven and oil quenched. After heat treatment, the helix is brokenat each of the notches whereby the arcuate leaf springs 64 and 66 areproduced.

The ends of the arcuate springs 64 and 66 are placed upon the endportions of the core member 50 and secured thereto by the rivets 68 and70. The metal band 72 is then strapped about the end 58 and the twosprings 64 and 66. Finally, a plastic covering, corresponding to thecovering 38 of FIG. 1, is molded about the fabricated rim core.

The manufacturing steps involved in making the steering wheel 10 of FIG.1 is generally similar. The rim core member 18 is formed similarly tomember 50. The arcuate leaf spring 24 is made in a manner identical tothe making of springs 64 and 66. The short arcuate springs 26 and 30 maybe made by stamping or by cutting segments from a helix of flat springwire. The assembly of the steering wheel 10 includes riveting thesprings 24, 26 and 30 to the ends 20 and 22 of the rim core member 18.The entire rim core assembly is enclosed by molding the member 38 aboutit.

The steering wheel having a rim core constructed in accordance with thisinvention is characterized by its economy of manufacture and itssuperior performance in a motor vehicle.

The foregoing description presents the presently preferred embodiment ofthis invention. Details of construction have been presented for purposesof illustration and are not to be considered limits of the invention.Alterations and modifications of the invention may occur to thoseskilled in the art that will come within the scope and spirit of thefollowing claims.

We claim:
 1. A steering wheel for a motor vehicle having a rim meanswith a flexible rim portion;said steering wheel comprising a hub and aspoke having its inner end connected to said hub; said rim means beingsecured to the outer end of said spoke; said rim means comprising arigid rim core member of generally arcuate shape in plan view; said rimmeans also including a flexible rim core member of generally arcuateshape in plan view secured to said rigid rim core member and combiningwith said rigid member to form a structure of annular shape; saidflexible rim core member being deflectable under an impact load imposedupon the mid point of said flexible member in a direction parallel tothe axis of rotation of said wheel; said rigid rim core member beingsubstantially rigid with respect to an impact load imposed upon the midpoint of said rigid member that is equal in magnitude and parallel indirection to said first mentioned impact load.
 2. A steering wheel for amotor vehicle according to claim 1 and including:said flexible rim coremember comprising a resilient spring member.
 3. A steering wheel for amotor vehicle according to claim 1 and including:said rigid rim coremember and said flexible rim core member each having a generallysemicircular shape in the plan view; said members being secured togetherin an end-to-end manner.
 4. A steering wheel for a motor vehicleaccording to claim 1 and including:said flexible rim core membercomprising a flat leaf spring member having one of its major surfaces ina plane perpendicular to the axis of rotation of said steering wheel;said flexible rim core member being substantially rigid againstdeflection with respect to a force imposed upon said flexible member inthe plane of said flat surface.
 5. A steering wheel for a motor vehiclecomprising a hub;a pair of spokes having their inner ends secured tosaid hub; a rigid rim core of generally arcuate shape in plan viewsecured to the outer ends of said spokes; said rigid core having firstand second ends; a spring metal rim core of arcuate shape in plan viewhaving spaced apart ends secured to said ends of said rigid core; saidrigid rim core and said spring metal rim core combining to form astructure of annular shape; said spring metal rim core being resilientlydeflectable under an impact load imposed upon the mid point thereof in adirection parallel to the axis of rotation of said wheel; said rigid rimcore being substantially rigid with respect to an impact load imposedupon the mid point thereof that is equal in magnitude and parallel indirection to said first mentioned impact load.
 6. A steering wheel for amotor vehicle according to claim 5 and including:said spring metal corecomprising a leaf spring member having a major flat surface lying in aplane perpendicular to the axis of said steering wheel.
 7. A steeringwheel for a motor vehicle according to claim 5 and including:first andsecond arcuate spring pieces overlaying the ends of said spring metalcore; attachment means securing said first and second arcuate springpieces and the ends of said spring metal core to said first and secondends of said rigid core.
 8. A steering wheel for a motor vehicleaccording to claim 5 and including:said first and second ends of saidrigid rim core having mounting surfaces; said spring metal rim corecomprising a leaf spring member; first and second relatively shortarcuate leaf spring pieces overlaying the ends of said leaf springmember; attachment means securing said first and second leaf springpieces and the ends of said leaf spring member to the first and secondends of said rigid core.
 9. A steering wheel for a motor vehicleaccording to claim 5 and including:said spring metal core and said rigidrim core each having a generally semi-circular shape in plan view.
 10. Asteering wheel for a motor vehicle comprising a hub, a rim and a spokeinterconnecting said hub and said rim;said rim having a rigid rimportion of arcuate shape in plan view; said rigid rim portion havingfirst and second ends; a resilient rim portion of arcuate shape in planview having spaced apart ends secured to said ends of said rigid rimportion to form an annular structure; said resilient rim portioncomprising a plurality of arcuate leaf springs arranged in flushengagement with each other; said resilient rim portions beingresiliently deflectable under an impact load imposed upon the mid pointthereof in a direction parallel to the axis of rotation of said wheel;said rigid rim portion being substantially rigid with respect to animpact load imposed upon the mid point thereof that is equal inmagnitude and parallel in direction to said first mentioned impact load.11. A steering wheel for a motor vehicle according to claim 10 andincluding:each of said plurality of arcuate leaf springs havingsubstantially the same length.
 12. A steering wheel for a motor vehiclecomprising a hub, a rim and a spoke interconnecting said hub and saidrim;said rim comprising a rigid rim core of generally arcuate shape inplan view having first and second end portions; said end portions havinga lesser cross sectional area than the portion of said rigid rim corebetween said end portions; a spring metal rim core of arcuate shape inplan view having spaced apart ends secured to said end portions of saidrigid core; said rigid rim core and said spring metal rim core combiningto define an annular structure; said flexible rim core being resilientlydeflectable under an impact load imposed upon said flexible member in adirection parallel to the axis of rotation of said wheel; said rigid rimcore being substantially rigid with respect to an impact load imposedupon said rigid core that is equal in magnitude and parallel indirection to said first mentioned impact load.
 13. A steering wheel fora motor vehicle according to claim 12 and including:each of said endportions having cross sectional areas that are progressively smallertoward the terminus thereof.
 14. A steering wheel for a motor vehicleaccording to claim 12 and including:each of said end portions having agenerally stepped configuration in side elevational view withprogressively smaller cross sectional areas toward the terminus thereof.15. A steering wheel for a motor vehicle according to claim 12 andincluding:said first end portion of said rigid rim core having a flatmounting surface; said spring metal rim core comprising a leaf springmember in flush engagement with said mounting surface; said first endportion having a curved surface that forms an extension of said mountingsurface and is spaced apart from said leaf spring member; attachmentmeans securing said leaf spring member to said first end portion of saidrigid core.